1. Field of the Invention
The present invention generally relates to a signal demodulating technology of a digital wireless communication transceiver module, and more particularly relates to a two-phase frequency shift keying (FSK) digital demodulator apply to the intermediate frequency (IF) frequency shift keying (FSK).
2. Description of the Prior Art
Recently, the development of the communication products is increasingly improved and the Internet is more and more commonly used. The emergency of the information technology (IT) household appliances and the use of the wireless communication, the digital broadcasting; and the broadband network have proved the coming of the IT century as well as leading to information transmission accurring more promptly and diverse, in order to match the increasing requirement of the IT products, the personal wireless communication technology becomes the attention-getting star in the recent years and the requirement of the wireless products is respectively enhanced.
In the wireless communication products, the radio frequency/intermediate frequency module is composed of the wireless transceiver unit, the signal composing unit, and the wireless emitting unit. Wherein the transceiver unit utilizes the radio frequency head, the mixer, the intermediate frequency amplifier, the demodulator, and other circuits for eliminating the interference signal or automatically gaining modulation. Basically, after amplifying, wave filtering, and composing the signal, which is received by the radio frequency/intermediate frequency module, the demodulator is utilized to demodulate and return the intermediate frequency to the original base frequency so as to use for the following process of the base frequency. Hence, the demodulator is an important part in the digital wireless communication transceiver module.
In the prior art, when the FSK demodulator of the modulation technology is utilized to perform the modulation of the intermediate frequency, a mixer is firstly utilized to perform the first frequency-descending to lower the intermediate frequency into a signal with a high Q value. Then, the signal is calculated via the complex calculating formula internally designed, such that the signal can be demodulated into the base frequency. Prior method will cause increasing the signal delaying time and the occupied counts of the logic gate counts. In addition, the RTL digital design circuit adopted by the prior FSK demodulator requires a larger chip area and the current consumption is correspondingly increased.
Hence, the main spirit of the invention is to provide a signal demodulating method of a two-phase frequency shift keying (FSK) digital demodulator, and then some disadvantages of well-known technology are overcome.